Question

Molecular mass of H2O

Answer 1

molar mass of hydrogen=1.008
molar mass of O=16
molar mass of H2O=16+2*1.008
=18.01528 g/mol is the molar mass of H2O

Answer 2

Atomic mass of hydrogen =1
But it is given H2 so 1*2 = 2
Atomic mass of oxygen =16

Now add hydrogens atomic mass and oxygens atomic mass
So 16 + 2 =18 u
Answer = 18u